Method of making hollow articles.



PATENTED AUG. 28, 1906.

S B L m ET LR HA W m E L L.O mH G m MK AA R M F E0 w WH T B APPLICATION FILED MAY24,1904.

Inventors: WIIHEFTI'H. Pratt, Alvarado LeRog Ellis,

Witnesses;

. stiflness and rigidity to retain its shape after;

UNITED, s A rns WILLIAM-"H. PRATT. AND jALvARAno LE ROY ELLISQQF LYNNQMASSAP- OHUSETTS, ASSIGNOR TO GENERAL RATION or NEW YORK.

PATENT orinoni ELECTRIC COMPANY, A GQRP O- METHOD OF MAKING- HOLLOW AR noLEs,

. Patented'Aug. 28, 19064 Application filed May 24, 1904 Serial No. 209,574.

To aZZ whom, it may concern:

Be it known that we, WILLIAM H. BRATT. .and A VARADO LE ROY ELLIs, citizens of the the following is a specification.

This invention relates to a method of making hollow articles, and especially hollow art-icles made from a number of convolutions of Wire or similar material having sufficient the'sup 0 ting-body on which it is formed is withdrawn. The process is particularly useful ,in the manufacture of small armatures used in electric meters and measuringinstrnments of the motor type.

- other material which enters into the "con struction of the completed article, applying a coat of Varnish or other suitable material to make the several convolutions of wire more nearly selfsup orting, 'and thenremoving the su porting- 0d by a lyin heat thereto an allowing it iz o run dut. The fusible body may be molded in any suitable manner and may be rovided with project-ions integral therewith or secured thereto for the purpose of giving the desired formation to'the completed article or holding the wire or other material in the proper relation until all the parts are in position, when they assist in su porting each other. The material for or t e parts of the completed article may be applied to the supporting-body in any convenient manner as, for instance, by a winding-machine if wire or similar material is usedand to facilitate this operation the body may be provided with. suitable openings through which a holding device may be inserted/to support the body and rotate it or move it in such other way as is necessary. If the completed article is to be used with other devices,

ing-body any desired metho of app heat thereto maybepursued; but we prefer to do this by immersing it in a bath of molten paraffinor such. other material as is used in making the supporting body. Paraflin is particularly adapted for this usefas it is fluid at a comparatively low temperature, and by using the same material or materials having substantially the same specific gravity in both the bath and the supporting-body the parts ofthe article formed on the body are not subjected to any undue strains when the latter runs out'after beingreduced to a fluid state by the heat.

In one aspect our invention accordingly consists in t e process of making an armature consisting of molding a body of fusible material, the conductors thereon,

and immersing said body and the conductors thereon in a heated bath of molten material. This rocess-is' of particular utility in the manufacture of armatures for meter-motors. In electric meters-it is essential that no magnetic material be used in thecore of the armature and that the weight of the movable element be reduced to a minimum'in order.

that the friction in the bearings shall be as small as possible and that there shall be the least ossible increase in this friction throughout t e life of the'meter. quirements, armatures for use in electric meter-motors have been commonly constructed heretofore by winding the armatureconductors over a light spool consisting of a.

central stem, usually of wood, having thin sheet-metal end pieces thereon, giving the armature the form of a cylinder having slightlyconed ends. We have found that a spherical To meet these rearmature is greatly to be preferred to this type, for the reasons that with circular arma tore-coils the weight of the armature which forms a large part of the weight on the stepbearin of the meter is considerably reduced, since t e minimum weight of wire per ampere-turn inclosinva given area is'required when circular coi s are used, and since the sheet-metal'sup orts over which the coils are wound can he made. much smaller, and also for the reason that making the armature spherical and the field-coils circular permits assembling these arts in a meter with a smaller clearance etween them than with other formsof armatures and field-coils, thus making the maximum number of the lines of g v s29,eo1

vention is not limited in any way, but is ap-..

lioable generally to the manufactureof hol ow armatures of any desired shape and many other articles widely different therefrom. The details of the process and the preferred mode of pbractioing the same will be I 5 etter understood y reference to the follow ing description, taken in connection with the accom anying drawings.

In t e drawings ,Figure 1 is an elevation of the completed armature. Fi 2 is a section of thefusible supportin -bo y ready to receive the armature-con uctors; and Figs. 3 and4 are a-plan and elevation, respectively,

of the supporting-body.

Referring first to Figs. 3 and 4, 1 indicates a body of parafiin or other similar material which can be reduced to a fluid or plastic state b heatin it to a tem erature so low,

that the article ormed thereon is not injured thereby. It is formed byopouring the material when in a molten state into a suitable.

mold; The body is spherical except that it is flattened at opposite sides, so that the crossmg of the,co1 s at the ends will build them out, and thus make the completed armature a perfect sphere. Projections 2 are formed integral with the body 1 to space the coils a art and hold them in proper relation until all are wound. If desired, however, the projections 2 may bewooden wedges ressed into openings in the body 1 and wit drawn therefrom after all the armature-coils are wound in place. A' central opening 3 is formed in the body and at each end is a shallow concentric depression '4. Transverse openings 5, as shown b dotted'lines in Fig. 3, are providedthrou'gh t e body to secure it on a winding-machine while the coils are being wound in place.

transverse line Figs. 2 and 4, and the two parts placed together to form the completed Ody. In the latter case theopenings 5 may edge. A. central shaft is' then inserted in the opening 3, and'this may be theshaft of the meter or a te nporary shaft to be withdrawn afterward and replaced byt'he meter-shaft.

We prefer, however to use a s lit sleeve 6 of aluminium, because of its lig tness, havin shoulders 7 formed thereon nearjits ends, an to force down over the ends 'ofsle'eve 6 and into the su porting-body'one or more clamps wound on. pro erly wound and leads taken 0E from If'desired for convenience in molding, the body 1 may be formed in two similar hemispherical parts, as shown by the the shaft of the meter. Over each end of the sleeve 6 we place a'thin stifi washer 9 of aluminium, which fits down into the depression 4 in the end of the body 1 and against the shoulder 7 on sleeve 6. We then insulate the outer surface of each washer 9 and the end of the sleeve 6 extending therethrough by cov.. ering them with shellacked paper 10 or other ,suitable insulating material.

The supporting-body is then. in the condition shown in Fig. 2 and is ready to receive the armatureconductors. We prefer to wind these conductors on with a winding-machine provided with a two-pronged fork to hold the body,

and we secure the latter on the machine by pressing the prongs through any pair ofrthe transverse openin s 5. A coil of the armature is then woun' on by revolvin the body 1 and guiding the wire so that t e desired number of turns are arranged in layers between two adjacent projections 2 on opposite sides of the supportm -body 1 and on either side of the sleeve 6, eads being taken off from the ends of the coil for connection to a commutatorsegment and the end of another coil. The body is then withdrawn from the forked holder of the machine and turned around, so that the forks can be inserted through the next pair of openings 5, when an other coil is wound on in a similar manner, and the operation is repeated until all the coils are in lace, In order to'hold the several convo utions together" better and to make them more nearly self-supporting, we apply a suitable varnish to the wire as it is en all the coils have been eac one for connection to the commutator and the other c'oils, we apply heat to the body 1 and melt then same, so that it flows out. We prefer to do this by immersing the armature in a bath of molten paraffin or other material of substantially the same s ecific gravity as that ofthe s11 porting-b0 y 1, so that no undue strain is p aced upon the armatureconductors. Fig. 1 shows the armature after all the paraffin has been withdrawn from its interior; It is now ready to be secured. to'the meter-shaft by inserting the atter through the split sleeve. 6 until in the properposition and then tightening up on the clamps 8.

- As shownin Fig; 1 and as described herein,

"the armature is exceedingly light relatively tothe amount .of torque it can be made to de- ,velop, has no magnetic material in its supporting structure, and isquite strong enough for the work it .must do and the strain it must withstand, and this is the type-of armature which we prefer to use. However, we do not wislito be understood as limited to the process v ofniaking this or any other type of armatu'reQas our {invention is of general applica- '.-tion to the manufacture of hollow armatures 8,.by whic thearmature maybesecured to 1 of different shapes and constructions andito heated bath of molten material.

other articles widely different therefrom, and We aim to cover all such applications'of the invention in the claims appended hereto.

hat we claim as new, and desire to secure by Letters. Patent of the United States, is-

1. The process of making a coil, consisting in molding a body of fusible material, Wind-. ing the coil thereon, varnishing the coil, and removing said body of fusible material by applying heat thereto.

2. The process of making an armature, consisting in molding a body of fusible material, Winding the armature-conductors thereon, and removing said body by-immersing said body and the conductors thereon in a 3. 'I he process of making an armature, consisting in molding a body of fusible material, Winding the armature-conductors thereon, and removing said body by immersing said body and ,the conductors thereon in a bath of said material reduced to a molten state.

4. The process of making an armature,

consisting in molding a body of fusible m ate.- rial having pro ect|ons thereon, winding the l armature-conductors about said body and between the projections, and applying heat to said materialto remove the same.

5. The process of making an armature, consisting in molding a body of fusible mate- 'rial, inserting a shaft therein centrally, placing Washers on the ends of the shaft and against the body, Winding the armature-conductors about the body, and applying heat to the body to remove the same.

6. The process of making an armature, consisting in molding a body of fusible material, inserting a shaft therein centrally, placing Washers on the ends of the shaft and against the body, insulating the Washers and the ends of the shaft extending therethrough, Winding the armature-conductors about the body, and applying heat to the body to re- I move the same.

In Witness whereof we have hereunto .set our hands this 21st day of May, 1904.

WILLIAM H. PRATT.

ALVARADO LE ROY ELLIS. Witnesses:

DUGALD MoK. McKILLoP,

JOHN J. WALKERI 

